Valleyite is a rare calcium iron oxide. Associated minerals include hematite, maghemite and luogufengite. It was first described from Menan Volcanic Complex, near Rexburg, Idaho and near Gillette, Wyoming, USA.
Is this valleyite?
2-step field checkRun through these checks against the specimen in your hand. The more boxes tick, the more confident the ID.
- 1Test the hardnessTry to scratch valleyite with a known reference. Valleyite sits at Mohs 1, softer than the next harder reference, harder than the previous one.
- 2Look at form & habitCrystal system: cubic. Typical habit: platy crystals, foliated masses, or coatings.
Often confused with
Valleyite vs. its common look-alikes, and how to tell them apart in the field.
Often found alongside valleyite
Minerals reported to co-occur with valleyite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- Ca₄Fe₆O₁₃
- Mohs hardness
- 1
- Density
- 3.1-3.2 g/cm³
- Transparency
- Opaque
- Crystal system
- Cubic
- Crystal habit
- Platy crystals, foliated masses, or coatings
- Rarity
- Rare
- Uses
- Collector
- Host rock
- An oxidation product of basaltic glass, on the surface of vesicles, formed during the early stage of the scoria formation (Idaho) and in paralava, fused sedimentary rock (Wyoming)
Where rockhounds find valleyite
Classic worldwide localities
- Menan Volcanic Complex, near Rexburg, Idaho and near Gillette, Wyoming, USA
Field-hunting tip
Where it forms: An oxidation product of basaltic glass, on the surface of vesicles, formed during the early stage of the scoria formation (Idaho) and in paralava, fused sedimentary rock (Wyoming). If you start seeing hematite, maghemite, luogufengite in float, you are in the right ground. Typical habit: platy crystals, foliated masses, or coatings. Train your eye for that shape before scanning the outcrop.
Common questions
How do you identify valleyite?+
Where is valleyite found?+
What rocks look like valleyite?+
What minerals are found with valleyite?+
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Find valleyite on the map
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